Air-Traffic Mistakes Surged Again in Fiscal 2013

However, Number of Most Serious Midair Close Calls Dropped Slightly

U.S. air-traffic-control errors continued to climb in fiscal 2013 rather than plateauing as federal aviation regulators previously projected, according to data slated to be released by the government.

There were roughly 6,700 instances of planes flying closer to each other than permitted in U.S. airspace in the 12 months through September, up nearly 50% from a record 4,394 events a year earlier, according to data compiled by the...